Spinal implant systems provide a rod for supporting and positioning the spine in response to the specific problem being corrected by the implant and the patient""s particular anatomy. The systems comprises a support rod, bolts secured to vertebrae and a connector that securely engages the support rod to the connecting bolts and allows the system to assume positions where the rod is maintained at various angles in response to the problem being corrected and the patient""s particular anatomy. Although implant systems currently available satisfy these basic needs, further refinements are needed in the design of the connection assemblies utilized. Connection assemblies are needed that: minimize the assembly preparation prior to installation; can quickly assume and maintain an approximate position in the initial phase of installation, then be quickly and easily locked into position to complete the installation; have the ability to be repositioned with minimal effort after initially secured; and require minimal space in the patient""s spinal region for installation.
It is one object of the present invention to provide a connection assembly for a spinal implant system having components that limit the rotation of a spinal implant rod in respect to a corresponding spinal implant bolt, cause the initially implanted system to assume and maintain a position that approximates its final position and allow the system to be easily secured when the appropriate position has been attained. The structure limiting rotation is an interface element having an internal stop within an internal circumference or internal periphery, the internal stop positioned to contact other internal structures such as two edges of a seat maintaining a second interface element. The nature of the internal stop and its placement allow the connection assembly""s size to be reduced without sacrificing the assembly""s performance.
In one aspect of the present invention, a connection assembly for connecting a spinal implant rod to a spinal implant bolt is provided, the assembly comprising: a rod connecting member having an opening for receiving a portion of the rod, and a first interface element on the rod connecting member; a bolt connecting member attached to the rod connecting member, the bolt connecting member having an opening for receiving a portion of the bolt, and a second interface element on the bolt connecting member; the first interface element being fixed against rotation relative to the rod connecting member and the second interface element having a disengaged condition wherein the rod connecting member and bolt connecting member are rotatable within a limited range relative to one another, the limited range defined by an internal stop element positioned within an inner periphery of one of the interface elements; and the first interface element and the second interface element having an engaged condition wherein the rod connecting member and bolt connecting member are fixed against rotation relative to one another. Connection assemblies according to this embodiment of the present invention have structural features that provide for reduction in the assembly""s size, that allow the assembly to approximate a final installed position early in the installation process while the assembly""s interface elements are in a disengaged condition and allow the assembly to be quickly and easily secured to maintain an appropriate position once the elements assume an engaged condition.
It is a further object of the present invention to provide connection assembly for connecting a spinal implant rod to a spinal implant bolt wherein the assembly can be initially secured and subsequently re-positioned and re-secured with minimal effort as needed. In one aspect of the present invention, a connection assembly for connecting a spinal implant rod to a spinal implant bolt is provided, the assembly comprising: a rod connecting member having an opening for receiving a portion of the rod; a first interface element on the rod connecting member; a bolt connecting member having an opening for receiving a portion of the bolt; a second interface element on the bolt connecting member, the first interface element being fixed against rotation relative to the rod connecting member and the second interface element being fixed against rotation relative to the bolt connecting member, the rod connecting and the bolt connecting members rotatably attached about a connection axis, one member opposing the other; interlocking structures on opposing surfaces of the interface elements, such that when the elements are engaged with one another, the interlocking structures prevent rotational movement of the interface elements relative to one another; and a compressible member positioned between the interface elements, the compressible member in its uncompressed state preventing the interlocking structures from engaging. Connection assemblies according to this embodiment of the present invention have a compressible member positioned between the interface elements that in its uncompressed state prevents engagement of the interlocking structures, in its compressed state allows the interlocking structures to become engaged to prevent rotation of one interface element relative to another interface element, and upon returning to its uncompressed state separates the interlocking structures associated with the interface elements allowing the interface elements to once again rotate for repositioning.
It is a further object of the present invention to provide a medical assembly comprising first and second assembled components, wherein the components are provisionally secured in their assembled configuration by a biocompatible material, and wherein the biocompatible material is disruptable during installation of the medical assembly. Additionally, the biocompatible material may also be capable of being resorbed by the body. Preferred embodiments of the present invention maintain their configuration during normal shipping and handling and during installation allow disruption of the provisionally secured component utilizing hand tools and forces reasonable within a surgical environment.
It is a still further object of the present invention to provide for an interface element having structural features that cooperate with other structural features of a connection system to restrict rotation of the interface element and any associated component about a central axis. In one aspect of the present invention, an interface element for use in a connection assembly is provided, the interface element comprising: a structure having at least one face; a central opening for receiving a structural element of a rod connecting member or a bolt connecting member and resist rotation relative thereto; and at least one internal stop element located about an inner periphery of the interface element. The utilization of interface elements of the present invention in connection assemblies allows the size of the assembly to be reduced without sacrificing the assembly""s mechanical strength. Connection assemblies utilizing the novel interface element take up less space within a patient while still facilitating installation by providing restricted rotation of the rod connecting and bolt connecting members. As a result, a spinal implant system utilizing the assembly can be smaller without sacrificing performance.
It is a still further object of the present invention to provide a method to provisionally secure a component of a medical device therein, but allow the secured component to be subsequently engaged or removed. In one aspect of the present invention, a method is provided for provisionally securing components of a medical device, the method comprising: providing at least two components of a medical assembly to be provisionally secured, the components having surfaces suitable for engagement; applying a biocompatible material to at least one of the surfaces; contacting the surfaces to be secured; and maintaining contact of the surfaces until the components have been provisionally secured. Components of medical devices secured by this method remain in place after manufacture and during shipment and subsequent handling and can be engaged as necessary with minimal effort utilizing common hand tools and forces appropriate to a surgical environment to effect installation of the device in the usual manner.